The modeling responses of heat budget in the Eastern China Seas to global warming

<p>Impacts of climate change on heat budget in the Eastern China Seas (ECSs) are estimated under the historical, RCP4.5 and RCP8.5 scenarios using an atmosphere-ocean coupled regional climate model system (REMO/MPIOM). Solar radiation contributes the largest heat source of the ECSs. The heat gain achieved by solar radiation is overruled by thermal radiation, latent heat flux and sensible heat flux released at the ocean surface. The air-sea heat exchange thus cools the ECSs, whereas an overall warming is found for the ECSs. An increased oceanic heat transport by ocean currents balances this reduced heat supply by the sea surface heat fluxes. In particular, the water transport through Taiwan Strait brings the largest amount of heat into the ECSs. Despite of an inward heat transport onto the ECS shelf caused by the Kuroshio intrusion occurring northeast of Taiwan, overall, the shelf break section acts as a heat sink for the ECSs. The net heat gain/loss by the Tsushima Strait is marginal. Under the climate projection scenarios, the net heat loss from the shelf break section reduces, probably associated with the change in surface wind. Thus the net heat transported into the ECSs through the lateral boundaries increases slightly under these scenarios, leading to an overall warming of the ECSs, relative to 20C run. Noteworthy, the warmer SST, along with strengthened wind, further enhances the surface evaporation, providing a negative feedback onto the net effect of oceanic transport.</p>

A Comparison between a Generalized Beta–Advection Model and a Classical Beta–Advection Model in Predicting and Understanding Unusual Typhoon Tracks in Eastern China Seas

A total of 163 tropical cyclones (TCs) occurred in the eastern China seas during 1979–2011 with four types of tracks: left turning, right turning, straight moving, and irregular. The left-turning type is unusual and hard to predict. In this paper, 133 TCs from the first three types have been investigated. A generalized beta–advection model (GBAM) is derived by decomposing a meteorological field into climatic and anomalous components. The ability of the GBAM to predict tracks 1–2 days in advance is compared with three classical beta–advection models (BAMs). For both normal and unusual tracks, the GBAM apparently outperformed the BAMs. The GBAM’s ability to predict unusual TC tracks is particularly encouraging, while the BAMs have no ability to predict the left-turning and right-turning TC tracks. The GBAM was also used to understand unusual TC tracks because it can be separated into two forms: a climatic-flow BAM (CBAM) and an anomalous-flow BAM (ABAM). In the CBAM a TC vortex is steered by the large-scale climatic background flow, while in the ABAM, a TC vortex interacts with the surrounding anomalous flows. This decomposition approach can be used to examine the climatic and anomalous flows separately. It is found that neither the climatic nor the anomalous flow alone can explain unusual tracks. Sensitivity experiments show that two anomalous highs as well as a nearby TC played the major roles in the unusual left turn of Typhoon Aere (2004). This study demonstrates that a simple model can work well if key factors are properly included.